This app works as a Ductulator and Pressure Loss (friction) calculator which has the following functions.
- Converts Duct Shape or Size to Another
 - Determines Sizes for a Given Friction Rate
 - Determines Sizes for a Given Velocity
 - Determines Sizes for a Given Velocity and a Friction Loss Rate (simultaneous output)
 - Determines the Airflow Rate for a Given Size and Friction Loss Rate
 - Calculates Friction Loss
 
https://ductulator.smacna.org/